1. Field of the Invention
This invention relates in general to terminating shielded electrical cables in electrical connectors, and more specifically to a combination of a cable preparation method, a connector shield structure and a crimping process for attaching a conductive braid of the cable to the connector shield.
2. Discussion of Related Art
There are some common methods of crimping the conductive braid or sheath of a coaxial electrical cable to a connector shield. In one method, crimped tabs formed with a connector shield body have sharp edges that penetrate a surrounding, insulative jacket of the cable to contact the conductive braid when the tabs are crimped around the cable. This is a fast method but produces a crimped interface with a weak retention force. A number of environments, particularly automotive, require a high retention force.
Another conventional method is characterized by a dual tubular structure. One tube, a ferrule, is a separate component and sandwiches the braid between the ferrule and a tubular part of the connector shield. Crimping the ferrule around the braid and tubular part of the shield provides a higher retention force, but requires handling of the loose ferrule and manual cable preparation to separate and terminate the braid. This method is also difficult and expensive to automate, so it is usually manually performed. Therefore, neither of these described methods is ideal for low-cost, mass-produced terminations of shielded cables for automotive environments.
A twisted pair shielded electrical cable also requires a better approach for termination to a connector shield. This cable has multiple wires comprising a non-circular inner core and wrapped by a shielding foil and braid. A traditional crimping method as described can create a reliable, high strength crimp interface, but the braid termination is time consuming and very hard to automate. The non-circular inner core requires protection from damage during the high force crimping process. This usually necessitates providing an internal, rigid tube between the braid and inner core, increasing the component count as well as putting another step in the assembly process.